The pathomorphology of a human xenotransplanted basaloid squamous cell carcinoma.

To elucidate some factors related to the malignant phenotype of an oral tumor with mixed cell population the question has been raised whether the biological behavior of the basaloid or the squamous cells show any difference in an immunosuppressed host organism. Basaloid squamous cell carcinoma (BSCC) surgically removed from sublingual location was xenotransplanted either subcutaneously or in the oral submucosa and the histology, ultrastructures, LDH isoenzyme pattern were investigated. The epithelial origin of the established tumor line (HTB-1) could be recognized according to the characteristic epithelial ultrastructures, while the type of the LDH isoenzymes proved its human origin. The squamous cell population dominating the parent surgical specimen of BSCC regressed during xenotransplantation in the subcutan location, on the contrary the basaloid cells grew and maintained the tumor. Interestingly the basaloid cells transplanted from the subcutis to the oral submucosa generated a squamous cell population with an infiltrative growth pattern. The xenografted BSCC offer a promising model to investigate the contribution of each cell populations in the malignant phenotype. The presented data indicate that the basaloid cells are responsible for maintaining the tumor cell population, but certain malignant features (i.e. infiltrative growth) is associated to the squamous cells which are generated from the basaloid cells only under specific circumstances. Thus this particular model system showed that different malignant features could be associated to the basaloid and to the squamous cell component.